Science & Research

At HeadRehab, everything we do has a fundamental basis in science. Our expert neuroscience research team has over 30 years of experience in the lab, teaching at the highest university levels, and collaborating with the finest research centers, such as the National Institutes of Health. Our scientific findings are regularly published in top peer-reviewed journals and meet the high standards of the research and clinical communities.

HeadRehab has received research grant funding from the Department of Defense, US Air Force, private charities supporting professional athletics, and investment dollars from the leaders in private healthcare and health technology.

Our research continues to explore the human brain, the effects of TBI, the changes in neuroperformance due aging and the onset of neurodegenerative diseases, and possible means of intervention and rehabilitation. We welcome the opportunity to partner with our clients to achieve research objectives and win grant funding. CONTACT US to learn more.

According to the Centers for Disease Control and Prevention (CDC), “A TBI is caused by a bump, blow or jolt to the head or a penetrating head injury that disrupts the normal function of the brain.” Learn more here.HeadRehab technology objectively tests brain function to identify and quantify deficits in Memory, Balance, Reaction Time, and Attention. Physicians, Researchers, and Sports Medicine professionals use this data as they manage concussion and study other neurodegenerative conditions.

There is growing empirical evidence that virtual reality (VR) is valuable for education, training, entertainment and medical rehabilitation due to its capacity to represent real-life events and situations with immersive environments. However, the neural mechanisms underlying behavioral confounds in VR environments are still poorly understood. In two experiments we examined the effect of fully immersive 3D stereoscopic presentations and less immersive 2D VR environments on brain functions and behavioral outcomes. In Experiment 1, we examined behavioral and neural underpinnings of spatial navigation tasks using electroencephalography (EEG) and HeadRehab virtual reality. In Experiment 2, we examined EEG correlates of postural stability and balance.

Our major findings showed that fully immersive HeadRehab 3D virtual reality induced a higher subjective sense of presence along with enhanced success rate of spatial navigation compared to 2D virtual reality. In Experiment 1, the power of frontal midline EEG (FM-theta) was significantly higher during the encoding phase of route presentation in the 3D VR. In Experiment 2, the 3D VR resulted in greater postural instability and modulation of EEG patterns as a function of 3D versus 2D environments. These findings support the inference that the fully immersive 3D enriched-environment requires allocation of more brain and sensory resources for cognitive/motor control during both tasks than 2D presentations. This is further evidence that 3D VR tasks using EEG may be a promising approach for performance enhancement and potential applications in clinical/rehabilitation settings.

2014.11.04 – International Journal of Psychophysiology
[courtesy of Elsevier publishing]

Validation of a Virtual Reality Balance Module for Use in Clinical Concussion Assessment and Management

The cornerstone of clinical concussion management is based on a combination of neuropsychological testing, balance assessment, and symptom evaluation,1,2 and this “gold standard” has remained largely unchanged. Although there are a variety of tools used in clinical balance assessments, the Balance Error Scoring System (BESS) and Sensory Organization Test (SOT) are 2 of the most common postural control assessments. Both of these tools are sensitive to concussion deficits.3–6 Typically, these tools indicate that postural stability reaches its worst 24 hours after concussion, with balance restored to pre-injury measures around 3 to 5 days postinjury.4,5,7,8

This short recovery window has raised concerns whether the currently used clinical balance tools are capable of picking up the residual deficits often associated with concussion. Although clinical management has remained consistent, continuing technological advancements have allowed for the creation of virtual reality (VR) paradigms. Virtual Reality (courtesy of HeadRehab, Inc) is designed to be an interactive environment generated by a computer that mimics the real world. An important component of the VR setting is that the participants inside the environment feel a strong sense of presence and the illusion of forward self-motion. In unpublished data (Slobounov S, Teel L, Newell K, Ray W, 2013), participants undergoing the HeadRehab VR balance test used in this study report a sense of presence of 9.2 (±1.4), with 0 being no sense of presence and 10 being high sense of presence. This high sense of presence found in the VR environment creates an immersive and more life-like setting, which is an added benefit to VR testing.

Compared with more traditional and clinically used concussion assessment tools, other benefits of VR are the 3-dimensional (3D) nature of the tests and transferability to real-life situations.9 Along with its ability to assess depth perception, several studies have found that decision-making processes and visual search behavior are different in a 2-dimensional (2D) versus a 3D environment.10–12 Along with creating a more realistic testing environment, these additional visual qualities have made VR modules susceptible to balance deficits seen after concussion up to 30 days post-injury.9,13–15 Although VR balance assessments are used in research settings, VR technology has yet to become a common part of clinical assessment.

To transition from a research to clinical setting, VR balance assessments must first be shown as a legitimate postural assessment tool. Therefore, the primary purpose of this study was to validate the HeadRehab VR balance assessment module for use in clinical settings. We hypothesized that the VR system would be significantly correlated with area of center of pressure (COP) data obtained from force platform. It should be noted that the COP area is considered a major clinical index of postural stability.16 Additionally, we hypothesized that concussed participants would have significantly worse balance measures compared with normal controls.

In conclusion, the HeadRehab Virtual Reality Balance Test is a valid tool for concussion assessment in clinical settings. This novel type of balance assessment may be more sensitive to concussion diagnoses, especially later (7-10 days) in the recovery phase than current clinical balance tools.

CHAPTER 4 – “Feasibility of Virtual Reality for Assessment of Neurocognitive, Executive and Motor Function in a Clinical Setting”

The purpose of this study was to investigate if Virtual Reality (VR) neurocognitive and executive motor function evaluation tools are susceptible to practice and fatigue effects similar to those currently used in a clinical practice. Fifteen athletically active and neurologically normal Penn State students participated in a VR “practice effect” study. Another 15 Penn State football players participated in an “effect of fatigue” study on neurocognitive, balance, and executive functions. HeadRehab, Inc developed the Virtual Reality software used in this study.

Subjects performed VR tests on several occasions. The statistical analysis was conducted to examine the VR measures as a function of testing session (practice effect), and physical fatigue (prior to and after full contact football practices). The number and type of full contacts during the football practices were assessed via a specially developed observational chart.

There are several major findings of interest. First, all subjects reported a “sense of presence” and “significant mental effort” while performing the VR tests. Second, neither effect of testing day (p> 0.05) nor effect of VR testing modality (p>0.05) was revealed by ANOVA. Third, physical fatigue did not influence the VR measures in the majority of football players under study (p>0.05). However, there was a reduction in several VR performance measures in football players who sustained prior concussive injuries.

The findings show that VR testing modalities implemented in this study and aimed to evaluate neurocognitive (spatial memory, attention), motor (balance) and executive functions may be used as a complementary tool in a clinical practice. VR testing modalities under laboratory conditions are easily transferable into field conditions, and can potentially be used as a sideline evaluation of subjects at risk for concussion.

There is evidence from EEG studies that unexpected perturbations to standing posture induce a differential modulation of cortical activity compared to self-initiated and/or predictable conditions. However, the neural correlates of whole body postural response to visually-induced perturbations on standing posture have not been examined.

Here we employ a novel experimental paradigm via combined Virtual Reality (developed by HeadRehab, Inc) and EEG measures to examine the effects of visually induced perturbations on the dynamics of postural responses. Twelve Penn State student-athletes without prior history of neurologic disorders and/or orthopaedic injuries participated in this study. There were no differences in response/reaction time measures between both spatially and temporally unpredictable and fully predictable conditions (p>.05).

However, significantly stronger modulation of frontal-central EEG theta activity was present prior to onset of unpredictable postural perturbations (p<=. 05) as induced by HeadRehab virtual reality sequences. It is postulated that enhanced EEG theta in unpredictable conditions reflects increased effort to recruit additional brain resources to meet the demands of the postural tasks.

Memory problems are one of the most common symptoms of sport-related mild traumatic brain injury (MTBI), known as concussion. Surprisingly, little research has examined Spatial Memory in concussed athletes given its importance in athletic environments. Here, we combine functional magnetic resonance imaging (fMRI) with a custom virtual reality (VR) paradigm from HeadRehab/InnovativeVR designed to investigate the possibility of residual functional deficits in recently concussed but asymptomatic individuals. Specifically, we report performance of Spatial Memory navigation tasks in a VR environment and fMRI data in 15 Division 1 athletes suffering from MTBI and 15 neurologically normal, athletically active age-matched controls.

No differences in performance were observed between these two groups of subjects in terms of success rate (94% and 92%) and time to complete the Spatial Memory navigation tasks (mean = 19.5 s and 19.7 s). Whole brain analysis revealed that similar brain activation patterns were observed during both encoding and retrieval among the groups. However, concussed athletes showed larger cortical networks with additional increases in activity outside of the shared region of interest (ROI) during encoding.

Quantitative analysis of blood oxygen level dependent (BOLD) signal revealed that concussed individuals had a significantly larger cluster size during encoding at parietal cortex, right dorsolateral prefrontal cortex, and right hippocampus. In addition, there was a significantly larger BOLD signal percent change at the right hippocampus. Neither cluster size nor BOLD signal percent change at shared ROIs was different between groups during retrieval. These major findings are discussed with respect to current hypotheses regarding the neural mechanism responsible for alteration of brain functions in a clinical setting.

Concussion in Athletics: Ongoing Clinical and Brain Imaging Research Controversies

Concussion, the most common form of traumatic brain injury, proves to be increasingly complex and not mild in nature as its synonymous term mild traumatic brain injury (mTBI) would imply. Despite the increasing occurrence and prevalence of mTBI, there is no universally accepted definition and conventional brain imaging techniques lack the sensitivity to detect subtle changes it causes. Moreover, clinical management of sports induced mild traumatic brain injury has not changed much over the past decade.

Advances in neuroimaging that include electroencephalography (EEG), functional magnetic resonance imaging (fMRI), resting-state functional connectivity, diffusion tensor imaging (DTI) and magnetic resonance spectroscopy (MRS) offer promise in aiding research into understanding the complexities and nuances of mTBI which may ultimately influence clinical management of the condition. New approaches using Virtual Reality technology are also explored.

In this paper, the authors review the major findings from these advanced methods along with current controversy within this field of research. As mTBI is frequently associated with youth and sports injury, this review focuses on sports‐related mTBI in the younger population.

There is a growing concern that traditional neuropsychological (NP) testing tools are not sensitive to detecting residual brain dysfunctions in subjects suffering from mild traumatic brain injuries (MTBI). Moreover, most MTBI patients are asymptomatic based on anatomical brain imaging (CT, MRI), neurological examinations and patients’ subjective reports within 10 days post-injury. Our ongoing research has documented that residual balance and visualkinesthetic dysfunctions along with its underlying alterations of neural substrates may be detected in “asymptomatic subjects” by means of Virtual Reality (VR) graphics incorporated with brain imaging (EEG) techniques.

Encoding of Visual–Spatial Information in Working Memory Requires More Cerebral Efforts than Retrieval: Evidence from an EEG and Virtual Reality Study

Visual–spatial working memory tasks can be decomposed into encoding and retrieval phases. It was hypothesized that encoding of visual–spatial information is cognitively more challenging than retrieval. To test this hypothesis electroencephalography (EEG) was combined with a HeadRehab virtual reality paradigm to observe the modulation in EEG activity. EEG power analysis results demonstrated an increase in theta activity during encoding in comparison to retrieval, whereas alpha activity was significantly higher for retrieval in comparison to encoding.

We found that encoding required more cerebral efforts than retrieval. Further, as seen in fMRI studies, we observed an encoding/retrieval flip in that encoding and retrieval differentially activated similar neural substrates. Results obtained from LORETA identified cortical sources in the inferior frontal gyrus, which is a part of dorsolateral prefrontal cortex (DLPFC) during encoding, whereas the inferior parietal lobe and precuneus cortical sources were identified during retrieval. We further tie our results into studies examining the default network, which have shown increased activation in DLPFC occurs in response to increased cerebral challenge, while posterior parietal areas show activation during baseline or internal processing tasks.

We conclude that encoding of visual–spatial information via the HeadRehab virtual reality navigation task is more cerebrally challenging than retrieval. Note: Previous versions of the HeadRehab virtual reality software are illustrated in this publication.

Application of Virtual Reality Graphics in Assessment of Concussion

Abnormal balance in individuals suffering from traumatic brain injury (TBI) has been documented in numerous recent studies. However, specific mechanisms causing balance deficits have not been systematically examined. This paper demonstrated the destabilizing effect of visual field motion, induced by virtual reality graphics in concussed individuals but not in normal controls. Fifty-five student-athletes at risk for concussion participated in this study prior to injury and 10 of these subjects who suffered MTBI were tested again on day 3, day 10, and day 30 after the incident. Postural responses to visual field motion were recorded using a virtual reality (VR) environment in conjunction with balance (AMTI force plate) and motion tracking (Flock of Birds) technologies. Two experimental conditions were introduced where subjects passively viewed VR scenes or actively manipulated the visual field motion. Long-lasting destabilizing effects of visual field motion were revealed, although subjects were asymptomatic when standard balance tests were introduced. The findings demonstrate that advanced virtual reality technology may detect residual symptoms of concussion at least 30 days post-injury.